1. Field of the Invention
This invention relates to semiconductor processing tools and, more particularly, to an apparatus for cleaning dispersing apertures configured within an input manifold of a deposition tool. The apparatus includes a rotating arm containing a vacuum source for drawing from the apertures deposits residing therein.
2. Description of Relevant Art
Most non-volatile solid films on a semiconductor substrate are formed by chemical-vapor deposition ("CVD"). Vapor phase chemicals that contain the required constituents react to form the solid films upon the substrate. A wide variety of amorphous or polycrystalline thin films may be deposited by CVD.
As a first step, reactant gases at a certain flow rate are introduced into a reactor. The gas species then move towards the substrate where they are absorbed and undergo migration and film-forming chemical reactions. Any remaining byproducts are then removed from the reactor. The chemical reactions that form the films nay take place not only on (or near) the wafer surface but also in the gas phase above the wafer surface.
CVD reactors are generally open-flow systems, in which gases continuously flow into the reactors, and gaseous byproducts are exhausted together with unused reactants and carriers. Reactant gases are typically carried by carrier gases such as hydrogen, nitrogen, or argon. Corrosive and hazardous gases pumped from the reactor are removed from the exhaust gas flow by a scrubber, and the scrubber output is then vented to the atmosphere. The input of the gases is controlled by mass-flow controllers and byproducts are removed from the reactor by a vacuum pump.
The design and operation of CVD reactors depends on a variety of factors, and hence they can be categorized in several ways. The first distinction between reactor types is whether they are hot-wall or cold-wall reactors, which depends on the method used to heat the wafers. The next criterion is their pressure regime of operation. The reactors can operate at atmospheric pressure, termed atmospheric-pressure CVDs (APCVDs) or operate at reduced pressure, termed low-pressure CVDs (LPCVDs). LPCVDs are further categorized into those where the energy input is entirely thermal and to those where the energy is partially supplied by a plasma, generally known as plasma-enhanced CVDs (PECVDs).
An example of a CVD reactor is shown in FIG. 1. Wafer 10 is placed upon wafer staging platform 12 inside chamber 21. Platform 12 is secured relative to housing 14 which surrounds the reactor. Housing 14 is removable to enable cleaning of the inside surface of chamber 21. Housing 14 attaches to the upper portion of the reactor via flanges 16 and 18 which engage with receptors 20 and 22. Receptors 20 and 22 are attached to the upper portion of the reactor. The reactant gases, which contain the necessary constituents to form the thin films, are introduced into the reactor through input manifold 24. Input manifold 24 comprises an input port terminating into a manifold which has, at one end of the manifold, a plate 26. Circular plate 26 comprises a plurality of apertures which are responsible of directing or dispensing reactant gases 28 delivered from the input port across the upper surface of wafer 10. Any unreacted gases and byproducts of the reaction are removed from chamber 21 through output manifold 30. Output manifold 30 is brought in communication with chamber 21 near the backside surface of platform 12, to evacuate byproducts as they pass from the plasma, reaction phase. A vacuum pump is attached (not shown) to manifold 30 to drawn byproducts from chamber 21. In the case of LPCVD reactors, the vacuum pump is also responsible for maintaining the chamber below atmospheric pressure.
CVD reactors can be used to deposit, for example, polysilicon, silicon dioxide (which may be formed from several different reactant gases), silicon nitride, phosphosilicate glass, and borophosphosilicate glass. Examples of reactant gases used in CVD reactors are silane, nitrous oxide, TEOS, TMP, TMB, oxygen, nitrogen, phosphine, and diborane. After several runs of the equipment, the deposition film accumulates on the sidewalls of the reactor and along the sidewall surfaces of the dispersing apertures periodically spaced through the input manifold. Eventually, cleaning of the apertures becomes essential in order to ensure proper flow of the reactant gases out of the input manifold. Accumulation on the dispersing apertures not only may clog those apertures, but can also be a source of contaminants which can deleterious fall onto the wafer surface.
Conventional cleaning of the apertures within plate 26 involves; manually wiping away accumulation with a cloth. Cleaning the plate using this method can spread the deposits from the apertures into the rest of the chamber thereby sourcing additional defect-arising sites. In addition, some of the deposits are pushed back through the apertures into input manifold 24 where they reside until gas flow is resumed. The particulate material becomes entrained within the gas flow and eventually falls upon the wafer. It would thus be desirable to employ a mechanism which can more effectively clean accumulated materials (i.e., particulate, film, debris, contaminant, etc.) from the input manifold plate. It would likewise be desirable to contain the removed material to prevent it from spreading elsewhere inside the reactor.